1. Field of the Invention
The present invention relates to hearing aids and to methods of operating hearing aids. The invention, more specifically relates to hearing aid systems comprising hearing aids, wireless transceivers and remote controls.
2. The Prior Art
Hearing aids capable of being operated by remote controls are known. Remote controls have been used primarily for selecting among different listening programmes stored in the hearing aids and for individual adjustment of the output levels of the hearing aids. The data bandwidth of the communications channels available in existing remote control systems for use in hearing aids is comparatively small and mainly used for simple commands like “adjust output level up one notch” or “change to program 2”, these command types taking up but a small number of bits of information. Existing wireless communications channels for the remote control of hearing aids in use today are usually one-way channels, i.e. it is not possible to transmit information from the hearing aid via the communications channel.
Recent developments in hearing aid signal processors encompass a multitude of different parameters and settings stored in non-volatile memory circuits in the hearing aid, each setting having a specific relation to the performance of the hearing aid, e.g. gain and compression levels in different frequency bands. The values of these parameters and settings will usually be decided and stored in the hearing aid during a fitting session with the user and a fitter. The effect of changing one or more parameters in the hearing aid may, to some extent, be monitored by the fitter through simulation in computer software, and, in some systems, monitored by reading out the parameters from the hearing aid in real-time, as described in the following.
An industry standard programming interface is the NOAH-Link® interface, manufactured by Madsen Electronics, Taastrup, Denmark. This programming interface comprises a transponder unit worn in a string around a hearing aid user's neck and connected, during use, to one or two hearing aids via cables and connectors. The transponder unit is capable of transmitting or receiving digital programming signals from a personal computer equipped with a similar transponder and running suitable software for the purpose of programming the hearing aid.
The transponders in the programming device and the personal computer preferably utilize the industry standard Bluetooth® wireless networking interface for communication, and the personal computer runs a version of the industry standard Compass® hearing aid fitting software. During use, a fitter of hearing aids may use this programming interface to program a prescription frequency response into the hearing aids of the user as decided, based on a hearing test, and according to the user's preferences. Data regarding the condition, programming, type, and serial number etc. of the hearing aids to be programmed may also be read out by the system for display in the computer. Although the link between the transponder and the personal computer is wireless, the system requires galvanic connection between the transponder of the programming device and the hearing aid circuitry.
However, connector sockets in hearing aids are complicated in design and manufacture, a potential source of error, and add significantly to the bulk of the hearing aids. The fitting of hearing aids with cables is a significant complication for the fitter.
U.S. Pat. No. 5,615,229 describes a magnetically coupled short-range communication system for transmitting audio signals between a magnetic transmission element and a magnetic receiving element in a hearing aid. The audio signals are transmitted as a time variant modulated, pulse coded data stream. This is a simplex system, and the magnetic receiving element in the hearing aid appears to be power-intensive, thus putting a great strain on the hearing aid battery.
WO 98 48526 devises a magnetic-induction time-multiplexed two-way short-range communications system for transmission and reception of signals between a telephone base unit and a portable headset in close proximity to said base unit. It has duplex capabilities and an adequate bandwidth, but the size of the receiver and transmitter in this system prohibits its use in hearing aid systems.
US 2004/0037442 describes a wireless binaural hearing aid system utilizing direct sequence spread spectrum technology to synchronize operation between individual hearing prostheses. This system enables two hearing aids to communicate wirelessly with each other for the purpose of synchronizing the sampling of the sounds picked up by the hearing aid microphones. A remote control is not involved in this system.
U.S. Pat. No. 5,390,254 discloses a hearing aid adapted for control by hand-held radio-controlled volume and tone controls and utilizing a radio link to enable enhanced real-time signal processing of the incoming sound via a remote processor. The wireless system utilized in this hearing aid is essentially based on analog processing, and although such a system could be made to function in practice it would be very cumbersome to use due to the size and power consumption of the components involved. However, no practical suggestions as to how such a wireless system might be implemented in practice are devised in U.S. Pat. No. 5,390,254, and no reference to any supporting literature in this respect are made.
EP 1 445 982 A1 describes an apparatus and method for mutual wireless communication between one or two hearing aids and a remote control unit for the purpose of controlling program selection and adjusting output volume. The communication is controlled by assigning different priorities to the hearing aids and the remote control unit and making each unit transmit in its own time slot according to the assigned priority. Apparently, no means to communicate from the remote control unit by other means than those provided for communication to the hearing aids, are provided.
EP 1 460 769 A1 discloses an electronic module and a mobile transceiver comprising several receivers for receiving electrical or electromagnetic signals carrying audio signals and a radio transmitter for transmitting radio signals carrying audio signals. The mobile transceiver comprises a prioritising module and a transmitter for transmitting audio received by one of the receivers to a hearing aid comprising a receiver. The actual transmission scheme used by the mobile transceiver is not disclosed, and no means for transmitting signals from the hearing aid to the mobile transceiver is disclosed.